Method of controlling plant growth



2,829,038 Patented Apr. 1, 1958 hoe METHOD OF CONTROLLING PLANT GROWTHPaul Ochsner, Uccle-Brussels, Belgium, assignor to Union 'ChimiqueBelge, S. A., Brussels, Belgium, 2 corporation of Belgium No Drawing.Application May 9, 1955 Serial No. 507,182

Claims priority, application Belgium May 14, 1954 6 Claims. (Cl. 71-2.6)

The present invention relates to the preparation of weed-killers. Theseproducts contain aromatic sulfamides corresponding to the generalformula in which R is hydrogen or halogen atom or a lower aliphaticradical; R is a lower aliphatic radical.

.The aromatic sulfamides are obtained by reacting a sulfamyl halide withan aniline substituted ornot. The products so prepared act as selectiveweed-killers, that is to say that they destroy some plants at adetermined stage of their growth while they do not attack other plants.

To determine the specific properties of weed-killers, three methods areused. In all cases, the first thing to do is to prepare a solution ofthe product in a solvent having itself no herbicidal action upon thetested plant.

Method A.A diluted solution of the examined product is sprayed on aplant.

Method B.-A drop of a solution of the examined product is put ondetermined places of a plant.

Method C.Definite quantities of a solution of the examined product areinjectedin the stalk of the plant with a micrometric syringe.

The two last methods give the possibility to distinguish between contactweed-killers which only cause necrosis I at .the treated places andteletoxics products which destroy all the plant.

For use, the products of the invention may be mixed with diluting,wetting, emulsifying and other agents. The object of the followingexamples is to show the selective action of aromatic sulfamides used asweed-killers. To this end, one of the three aforesaid methods is appliedto'various monoor di-cotyledons such as: oats, beet, chicory, wheat,beans, flax, lucern, corn-salad, turnip, daisy, radish and tomatoes.

Example 1.-Prepar atin of N,N-dim-ethyl-N'- (4-methylphenyl) suljamideExample 2.'-Prepar ation of N,N-dimethyl- N'-(3-chlorophenyl) vsulfamideA mixture of 225 gr. (2 moles) of m-chloraniline and 159 g'r. (1.1 mole)of dimethylsulfamyl chloride dissolved in 600 ml. of anhydrous benzeneis heated under reflux for 5 hours. After cooling, the m-chloranilinehydrochloride is extracted by means of a diluted solution ofhydrochloric acid. The residue obtained after distillation of thebenzene is dissolved in a diluted solution of sodium hydroxide.

Activated charcoal is added after filtration; the filtrate is acidifiedwith hydrochloric acid. The crystals formed are filtered under vacuumand dried. 121 gr. N,N-dimethyl-N-(3-chlor0phenyl) sulfamide (meltingpoint 88 C.) are so obtained. The yield is 51%.

In the same way, following compounds are prepared:

M. P., C. N,N-dimethyl-N'-phenylsulfamide .Q 61-63N,N-diethyl-N-phenylsulfamide 32N,N-dimethyl-N'-(4-chlorophenyl)sulfamide 53 Example 3.-Preparati0n ofN,N-diethyl-N'-(3-chl0r0- phenyl) sulfamide and N,N diethyl N (4chlorophenyl)sul amide N,N diethyl N (3-chlorophenyl)sulfamide-boilingpoint l50 C./0.02 mm. Hg. N,N-diethyl-N'-(4-chlorophenyl)sulfamidc, M.P. 50 C.

are new products. They are obtained as described in Examples 1 and 2.

Example 4.Acti0n of N,N dimethyl N'-(4 chloropheHyDsuIfamide ongermination (Method A) Seeds of oats, beet, chicory, wheat, fiax,lucern, cornsalad, daisy and radish were sowed in mould contained tountreated plants has been observedfor the chicory the flax, the radish.After four weeks, the young sprouts looked as follows:

Oats: reduced size Beet: partial attack Chicory: partial destructionWheat: no action, size somewhat higher than that o the untreated plantsFlax: partial attack Lucernz' partial destruction Corn-salad: partialdestruction Daisy: no action Radish: partial destruction Witha doubleconcentration in sulfamide, a complete destruction has been observedafter four weeks for the young sprouts of chicory, flax, lucern, daisyand radish.

In conclusion, the N,N-dimethyl-N'-(4-chlorophenyl) sulfamide has noaction on wheat and aflittle one on cats. The elfect of theconcentration is also to be observed for daisy, while this effect is notobserved for beet.

Example 5.-Acti0n of N,N dimethyl N (4 chlorophenyl)sulfamide on youngsprouts (Method A) The same seeds as in Example 4 were sowed. One

week after germination, the young sprouts were treated with a solutionof 0.5% (by volume) of N,N-dimethyl- N-(4-chlorophenyl) sulfamide. Tendays after the treat ment, the following results have been observed. a

3 Oats: nearly complete destruction Beet: nearly complete destructionand burns Chicory: complete destruction Wheat: size smaller than theblanks Flax: complete destruction Lucern: complete destructionCorn-salad: no action Daisy: no action Radish: partial destruction Witha concentration of 1% of the active product, the same effects butincreased, have been observed.

In conclusion, the herbicidal action of the examined product is fasterand sharper on young sprouts than on the seeds at the germination time.

Example 6.Action of N,N-dimethyl-N'-(3-chlorophenyDsuZfamide ongermination (Method A) The operation is the same as in Example 4, but asolution of 0.5% (by volume) of N,N-dimethyl-N-(3-chlorophenyl)sulfamideis used. After four weeks, the following results are observed:

Oats: slight yellowing Beet: no action Chicory: a few plants are fadedWheat: size smaller than the blanks Flax: a few plants are destroyedLucern: no action Corn-salad: partial destruction Daisy: no actionRadish: partial destruction.

With a concentration of 1% (by volume) of the active product, thecomplete destruction of the young sprouts of chicory and radish isobserved.

In conclusion, there is a marked action of the product on Wheat; on thecontrary no destruction is observed on beet and lucern although inExample 4 partial attacks are noted.

Example 7.Action of various weed-killers on the turnip (Method B)Compound 6: N,N-diethyl-N-(3-ehlorophenyl)sulfamide Compound 7:N,N-diethyl-N-(4-chlorophenyl)sulfamide C. M. U.:N-(p-chlorophenyl)-N',N-dmethylurea U. R. A. B.:N-phenylN',N'-dimethylurea.

About 40 drops of 0.005 ,ml. of a solution at 0.5 or 1% of aforesaidproducts in alcohol are put on two leaves of a turnip plant.

Compound 1 causes only necrosises which disappear after a few days.

Compound 2 causes necrosises which do not disappear, the leaves aredestroyed after 4 weeks.

Compound 3 in solutionat 1% kills the plants within 7 days.

Compound 4 in solution at 0.5% causes necrosises which extend to thecomplete surface of the leaves, but there is no mortality within 25-days; in solution at 1% it kills the plant within 5 to 7 days.

Compound 5 has a weak activity of which the effects are practically thesame asthose of compound 2 (destruction after 4 weeks).

4 Compounds 6 and 7 act practically as the compounds 3 and 4, in otherwords they kill the plant in 5 to 7 days when in solution at 1%.

To obtain the same results 10 days are necessary with the U. R. A. B.and 12 days with C. M. U.

Example 8.Acli0n of various weed-killers on tomatoes (Method B) Over thecompounds 3 and 4 and 6 of Example 7, following products were examined:

C. M. U: N-(p-chlorophenyl)-N',N-dimethylurea 2,4 D: sodium2,4-dichlorophenoxyacetate D. N. O. C.: ammonium4,o-dinitro-orthocresolate NaOCl sodium chlorate As in the foregoingexample, 0.2 cm. in drops of a solution at 0.5 or 1% are put on twoleaves of the plant.

The most active products are the compounds 3 and 6, i. e. theN,N-dimethyland N,N-diethyl-N-(3-chlorophenyl)sulfamides, which insolution at 0.5% cause deep burns on all the leaves and in solution at1% kill the plants within 7 days. Compound 4 is slightly less active.The sodium chlorate causes a slow decaying of the plant by dessicationof the treated places. The action of the 2,4 D and the C. M. U. isslower than those of the aromatic sultan-tides at a concentration of 1%;on the contrary an opposite effect is observed at a concentration of 0.5As to the D. N. O. C., it acts practically as the NaOCl in other wordsas contact weed-killer.

Example 9.--Action of the weed-killers on the beans' (Method B) Plantstreated according to Method B are destroyed within 14 days by the C. M.U. and within 18 days by the U. R. A. B. They are not destroyed by thearomatic sulfamides (compounds 1 to 7 of Example 8) at a concentrationequal to 1%.

Example 10.--Action of the weed-killers on tomatoes (Method C) Aninjection of 0.15 mg. of N,N-dimethyl-N'-(4-chlorw phenyl)sulfamide inthe stalk of a tomato plant causes its destruction within 6 days.

To obtain a same result, 20 days are necessary with .an equal quantityof 2,4 D (sodium 2,4-dichlorophenoxy* acetate). In the same conditions,the D. N. 0. C. (ammonium 4,6-dinitroorthocresolate) causes deepnecrosise's at the place of the injection, but not the mortality of theplant.

The foregoing examples clearly demonstrate that the aromatic sulfamidesact as selective weed-killers.

I claim:

1. A method for the control of plant growth which comprises applying tothe plant foliage an herbicidal amount of an aromatic sulfamidecorresponding to the formula -NH--S Or-N 5 comprises applying to theplant foliage an herbicidal amount ofN,N-dimethyl-N-(4-chlorophenyl)sulfamide.

5. A method for the control of plant growth which comprises applying tothe plant foliage an herbicidal amount ofN,N-diethyl-N'(3-ch1orophenyl)sulfamide.

6. A method for the control of plant growth which comprises applying tothe plant foliage an herbicidal amount ofN,N-diethyl-N-(4-chlorophenyl)sulfamide.

6 References Cited in the file of this patent UNITED STATES PATENTSBattegay May 4, 1937 OTHER REFERENCES Wheeler et al: J ournal ofAmerican Chemical Society, vol. 66, pages 1242-3 (1944).

1. A METHOD FOR THE CONTROL OF PLANT GROWTH WHICH COMPRISES APPLYING TOTHE PLANT FOLIAGE AN HERBICIDAL AMOUNT OF AN AROMATIC SULFAMIDECORRESPONDING TO THE FORMULA